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1989 xr250 rocker box torque sequence

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My son's friend has drug a 1989 xr250 back to life. He had to replace the cam and rocker box to get it going. He rode it for about 10 minutes, then a rattle started. I helped him pull the rocker box back off and it looks like the cam bearing (on the opposite side of the cam chain) had slid off.

 

We reassembled and everything seems to cycle properly again. I didn't notice an extreme amount of wear on either bearing surface. Could it be that he didn't torque the rocker cover down correctly?  Is there a specified sequence to re-installation of the rocker box? 

 

I know he should get a manual asap, but I was trying to help him get it back together this time. He has worked hard on it, and paid for it by mowing lawns, so I kinda feel for him. 

 

Any help would be appreciated. 

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It's probably the wrong gasket.  Use the expensive oem gasket with no sealer.  It must be .010" thickness.  DO NOT USE AN AFTERMARKET GASKET ON THE ROCKER BOX.

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Thanks for the tip Baja Rambler. I believe he is using the original oem gasket. We will measure the thickness tonight to be sure. 

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Thanks for the tip Baja Rambler. I believe he is using the original oem gasket. We will measure the thickness tonight to be sure. 

 

I forgot to mention that the oem gasket is steel.  It acts as a shim at the cam journals.  Too thick and the cam jumps up and down, too thin and the bearings are clamped down and don't turn freely.  Sealer has thickness, too, and causes problems.  Paper gaskets are no good here as they compress.  

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Thanks for the replies guys. We verified the gasket was .010 thick. He is going to reassemble and try again. 

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2 dowel pins (#25) keep the cam and bearings in place.  Don't forget to install them.

 

XR250R89Cam.jpg

 

:ride:

Edited by ramz

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2 dowel pins (#25) keep the cam and bearings in place.  Don't forget to install them.

 

XR250R89Cam.jpg

 

:ride:

 

You 'Ol fart. You still alive?

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